1. Field of the Invention
This invention relates to thrust bearings and more particularly to thrust bearings adapted to reduce the transmission of energy from the rotating shaft to the foundation or structure within which the bearing operates.
2. Background Information
A typical thrust bearing of the Kingsbury type such as for example U.S. Pat. Nos. 1,425,979 and 1,444,839, the disclosures of which are hereby incorporated by reference, include a collared shaft rotating within a stationary platform. A plurality of sector like shoes are mounted in a carrier which is mounted in the stationary platform. The sector like shoes are adapted to be thrust by means such as a hydraulic power source acting through axially movable pistons to press against the collar on the shaft to compensate for axial thrust that may be present along the axis of the shaft. Typically, the pistons are supported by pressurized fluid through a manifold, piping and several fluid flasks and a thin film of fluid separates the collar face and the shoes. The fluid system provides mass, stiffness, and damping properties to the shafting system which can in turn be tuned to provide vibration damping at certain frequencies. This arrangement is generally called a vibration reducer mechanism.
A thrust bearing is subjected to both constant axial thrust loads and cyclic thrust loads resulting from constant and cyclic end loads on the shaft. For a vibration reducer mechanism to operate properly, the path of load should be from the shaft collar through the fluid film into the thrust shoe to the vibration reducer piston through the fluid and into the thrust bearing housing. Residual vibration components are also transmitted to the stationary platform via the thrust bearing foundation where the cyclic component can stimulate vibrations of the stationary platform. Such vibrations can then be undesirably transferred into the surrounding medium causing noise or damaging vibrations in surrounding areas.
Thrust shoes, usually six to eight in number currently represent a direct path and therefore a vibration or sound short to the bearing housing due to their mounting arrangement. Each thrust shoe is positioned by metal to metal contact with the housing and the housing supports the weight of the shoes, torsional reactions and drag due to allowed bearing misalignment. Depending on the application of the bearing, total drag forces from these sources can be substantial.
There is a need for a thrust bearing shoe carrier that isolates the drag forces from the bearing housing and consequently isolates these drag forces from the stationary housing in which the bearing is located.